<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>Title</title>

  <style>
    .active {
      color: red;
    }
  </style>
</head>
<body>

<div id="app">
  <!--<h2 class="active">{{message}}</h2>-->
  <!--<h2 :class="active">{{message}}</h2>-->

  <!--<h2 v-bind:class="{key1: value1, key2: value2}">{{message}}</h2>-->
  <!--<h2 v-bind:class="{类名1: true, 类名2: boolean}">{{message}}</h2>-->
  <h2 class="title" v-bind:class="{active: isActive, line: isLine}">{{message}}</h2>
  <h2 class="title" v-bind:class="getClasses()">{{message}}</h2>
  <button v-on:click="btnClick">按钮</button>
</div>

<script src="../js/vue.js"></script>
<script>
  const app = new Vue({
    el: '#app',
    data: {
      message: '你好啊',
      isActive: true,
      isLine: true
    },
    methods: {
      btnClick: function () {
        this.isActive = !this.isActive
      },
      getClasses: function () {
        return {active: this.isActive, line: this.isLine}
      }
    }
  })
</script>

</body>
</html>